X-ray Scintillation Research Articles

Application of Sm3+ doped Gd2O3–Y2O3–ZnO–B2O3 glass for development of X-ray imaging scintillator

The X-ray scintillator materials are mostly made from single crystal. The limitations are high productive cost, and the process of producing is complex. There are numerous studies about developing new scintillators by using glass that are easier preparation and lower cost. This study tries to produce a new series of borate glass doped with Sm3+ in 20Gd2O3:10Y2O3:10ZnO: (60-x)B2O3:xSm2O3 formula with varying concentrations of Sm2O3. The samples were measured and analyzed by physical, optical, luminescence and scintillation properties. The results showed that the density increased after increasing the Sm2O3 concentration. The strong emission intensity was observed from photoluminescence and radioluminescence measurements, and the concentration quenching was observed at 0.5 and 1.0 mol% of Sm2O3 respectively. The strongest emission peak of Sm3+ ion is located at 600 nm that corresponds to f-f transition of 4G5/2 to 6H7/2 level. Moreover, we found that the Sm3+ luminescence at 600 nm emission wavelength increases (up to 0.5% mol), while the Gd3+ emission wavelength at 313 nm decreases, attributed to the energy transfer (ET) from Gd3+ ions to Sm3+ ions. X-ray imaging was also observed by using Synchrotron X-rays. These results suggest that the developed glasses could be applied to X-ray scintillators material, especially imaging applications.

Crystal Growth of Quaternary AkRE2Si2S8 (Ak = Ca and Sr; RE = La-Tb) Thiosilicates Using Flux-Assisted Boron Chalcogen Mixture Method: Exploring X-ray Scintillation, Luminescence, and Magnetic Properties.

We report on the detailed structural analysis of a series of 11 new quaternary rare earths containing thiosilicates, AkRE2Si2S8 (Ak = Ca and Sr; RE = La, Ce, Pr, Nd, Sm, Gd, and Tb), synthesized using the flux-assisted boron chalcogen mixture method. High quality crystals were grown and used to determine their crystal structures by single crystal X-ray diffraction. All members of the AkRE2Si2S8 series crystallize in the trigonal crystal system with space group R3̅c (space group no. 167). Polycrystalline powders were used for physical property measurements, including magnetic susceptibility, diffuse reflectance in the UV-visible range, and scintillation. Magnetic measurements indicated that CaRE2Si2S8 (RE = Nd and Tb) exhibits paramagnetic behavior with a slightly negative Weiss constant. The band gaps of the materials were determined from diffuse reflectance data, and optical band gaps were estimated to be 2.5(1) and 2.9(1) eV for CaCe2Si2S8 and CaGd2Si2S8, respectively. CaCe2Si2S8, CaTb2Si2S8, and SrCe2Si2S8 exhibited intense green luminescence upon irradiation with 375 nm ultraviolet light and, furthermore, scintillated when exposed to X-rays. Radioluminescence measurements of CaCe2Si2S8 powder revealed green emission with an intensity approximately 14% of that emitted by bismuth germanium oxide powder.

One-Dimensional Copper-Doped Rb2AgI3 with Efficient Sky-Blue Emission as a High-Performance X-ray Scintillator.

Scintillators have garnered heightened attention for their diverse applications in medical imaging and security inspection. Nonetheless, commercial scintillators encounter challenges with costly rare-earth metals and toxic elements like thallium (Tl), driving the need for sustainable, cost-effective, and eco-friendly alternatives to meet contemporary X-ray detection demands. This study focuses on exploring the potential of Cu+-doped Rb2AgI3 as an effective metal halide (MH) scintillator. One-dimensional (1D) Rb2AgI3 and Cu+-doped Rb2AgI3 single crystals (SCs) were synthesized by using the conventional temperature-lowering crystallization method. When excited by UV light, Cu+-doped SCs emitted a broad sky-blue light at 490 nm with a high photoluminescence (PL) quantum yield (PLQY) of 76.48%. Remarkably, under X-ray excitation, these Cu+-doped SCs demonstrated an outstanding light yield of 36,293 photons MeV-1, a relatively low detection threshold of 1.022 μGyair s-1, and a rapid scintillation decay time of 465 ns. The prepared translucent scintillation film has good uniformity and flexibility, with a high spatial resolution of 10.2 lp mm-1. These results position Cu+-doped Rb2AgI3 as a leading candidate among promising X-ray scintillators, offering superior scintillation light yield, excellent stability, and nontoxicity.

A Thermo-Responsive MOFs for X-Ray Scintillator.

Thermo-responsive smart materials have aroused extensive interest due to the particular significance of temperature sensing. Although various photoluminescent materials are explored in thermal detection, it is not applicable enough in X-ray radiation environment where the accuracy and reliability will be influenced. Here, a strategy is proposed by introducing the concept of radio-luminescent functional building units (RBUs) to construct thermo-responsive lanthanide metal-organic frameworks (Ln-MOFs) scintillators for self-calibrating thermometry. The rational designs of RBUs (including organic ligand and Tb3+/Eu3+) with appropriate energy levels lead to high-performance radio-luminescence. Ln-MOFs scintillators exhibit perfect linear response to X-ray, presenting low dose rate detection limit (min ≈156.1 nGyairs-1). Self-calibrating detection based on ratiometric XEL intensities is achieved with good absolute and relative sensitivities of 6.74 and 8.1%K-1, respectively. High relative light yield (max ≈39000 photons MeV-1), imaging spatial resolution (max ≈18 lpmm-1), irradiation stability (intensity ≈100% at 368 K in total dose up to 215 Gyair), and giant color transformation visualization benefit the applications, especially the in situ thermo-responsive X-ray imaging. Such strategy provides a promising way to develop the novel smart photonic materials with excellent scintillator performances.

Large-Area Transparent Antimony-Based Perovskite Glass for High-Resolution X-ray Imaging.

Nonlead low-dimensional halide perovskites attract considerable attention as X-ray scintillators. However, most scintillation screens exhibit pronounced light scattering, which detrimentally reduces the quality of X-ray imaging. Herein, we employed a simple and straightforward solvent-free melt-quenching method to fabricate a large-area zero-dimension (0D) antimony-based perovskite transparent medium, namely (C20H20P)2SbCl5 (C20H20P+ = ethyltriphenylphosphine). The transparency is due to the large steric hindrance of C20H20P+, which hinders the formation of crystals during the quenching process, thus forming a glass with low refractive index and uniform structure. This medium exhibits a high transmittance exceeding 80% in the range of 450-800 nm and shows a large Stokes shift of 245 nm, thereby minimizing light scattering, mitigating self-absorption, and enhancing the clarity of X-ray imaging. Moreover, it exhibits a high radioluminescence light yield of ∼12,535 photons MeV-1 and displays a high X-ray spatial resolution of 30 lp mm-1 owing to its high transparency. This study presents an alternative candidate for achieving high-quality X-ray detection and extends the applicability of transparent perovskite scintillators.

Photoluminescence-Tunable organic phosphine cuprous halides clusters for X-ray scintillators and white light emitting diodes

Low-dimensional cuprous clusters demonstrate fascinating luminescent properties due to their uniquely diversified charge transfer excited states, which imply it could be ideal candidate for multifunctional applications, such as X-ray scintillators and white light emitting diodes (WLED). However, it is still challenge for low-dimensional cuprous clusters that how to regulate the emission performance to meet the requirements of the specific applications. In this work, we prepared a series of luminescent organic cuprous iodide clusters, (IPP)CuI2 and (IPP)2CuI3, which show tunable emission property by simply component regulation. The (IPP)CuI2 with IPP: CuI = 1: 0.75 show the best scintillator property with super-low detection limit of 62.29 nGy/s and high light yields of 75793.83 photons/MeV which is far beyond most organic copper halide scintillators. A series of clear digital radiography (DR) with high spatial resolution of 10.2 lp/mm and a reconstructed 3D model based on computed tomography (CT) were successfully obtained by the prepared scintillation screen. Moreover, the single-component WLED based on accurately component regulation (IPP)CuI2 with IPP: CuI = 1: 0.99 exhibits pure white emission with a high CRI (color rendering index) of 82. The luminescence mechanism of charge transfer excited states in tunable emission (IPP)CuI2 was also investigated. Our works not only provide a kind of ideal materials applied for high-performance single-component WLED and scintillator but also reveal the large potential of low-dimensional organic cuprous halides as luminescent material for multifunctional applications.

Mn(II)-Based Metal Halide with Near-Unity Quantum Yield for White LEDs and High-Resolution X-ray Imaging.

Metal halides have drawn great interest as luminescent materials and scintillators due to their outstanding optical properties. Exploring new types of phosphors with easy production processes, excellent photophysical properties, high light yields, and environmentally friendly compositions is crucial and quite challenging. Herein, a novel Mn(II)-based metal halide (4-BTP)2MnBr4 was produced using a facile solvent evaporation method, which exhibited a strong green emission peaking at 524 nm from the d-d transition of tetrahedral-coordinated Mn2+ ion and a near-unity quantum yield. The prepared white light-emitting diode device has a wide color gamut of 100.7% NTSC with CIE chromaticity coordinates of (0.32, 0.32). In addition, (4-BTP)2MnBr4 demonstrates excellent characteristics in X-ray scintillation, including a high light yield of 98 000 photons/MeV, a sensitive detection limit of 37.4 nGy/s, excellent resistance to radiation damage, and successful demonstration of X-ray imaging with high resolution at 21.3 lp/mm, revealing the potential for application in diagnostic X-ray medical imaging and industry radiation detection.

Novel Tb3+ doped borophosphate glass scintillator for X-ray imaging

In this study, we introduce an efficient green-emitting material made from Tb3+ doped borophosphate scintillating glass for X-ray imaging. An influence of Tb2O3 concentration on the physical, optical, luminescent, and scintillation properties of glasses were investigated. The glass density and refractive index increase, while the molar volume and Tb3+ inter-ionic distance decreases with Tb2O3 addition. These glasses absorb the photons in range of UV, Vis, and NIR. The excitations by UV and X-ray on glasses causes the strong green emission centered around 545 nm by the 5D4 → 7F5 transition of Tb3+. The energy transfer from Gd3+ to Tb3+ was occurred in this emission. The glass doped with 4 mol% of Tb2O3 demonstrates the highest emission intensity at 545 nm due to the concentration quenching. The decay time of glasses are in few milliseconds. The integral X-ray scintillation efficiency of 4 mol% doped glass is 52% compared to that of BGO crystal. Additionally, this glass was proceeded in the X-ray imaging and yielded the image with satisfied resolution, characteristics and MTF values, compared to that obtained from YAG:Ce crystal. The developed glass has a potential for X-ray imaging applications, especially in the medical imaging, flaw detection, and security inspection.

Bright and durable scintillation from colloidal quantum shells

Efficient, fast, and robust scintillators for ionizing radiation detection are crucial in various fields, including medical diagnostics, defense, and particle physics. However, traditional scintillator technologies face challenges in simultaneously achieving optimal performance and high-speed operation. Herein we introduce colloidal quantum shell heterostructures as X-ray and electron scintillators, combining efficiency, speed, and durability. Quantum shells exhibit light yields up to 70,000 photons MeV−1 at room temperature, enabled by their high multiexciton radiative efficiency thanks to long Auger-Meitner lifetimes (>10 ns). Radioluminescence is fast, with lifetimes of 2.5 ns and sub-100 ps rise times. Additionally, quantum shells do not exhibit afterglow and maintain stable scintillation even under high X-ray doses (>109 Gy). Furthermore, we showcase quantum shells for X-ray imaging achieving a spatial resolution as high as 28 line pairs per millimeter. Overall, efficient, fast, and durable scintillation make quantum shells appealing in applications ranging from ultrafast radiation detection to high-resolution imaging.

Circularly Polarized Luminescence Induced by Hydrogen-Bonding Networks in a One-Dimensional Hybrid Manganese(II) Chloride.

Chiral hybrid metal halides hold great potential as circularly polarized luminescence light sources. Herein, we have obtained two enantiomeric pairs of one-dimensional hybrid chiral manganese(II) chloride single crystals, R/S-(3-methyl piperidine)MnCl3 (R/S-1) and R/S-(3-hydroxy piperidine)MnCl3 (R/S-2), crystallizing in the non-centrosymmetric space group P212121. In comparison to R/S-1, R/S-2 single crystals not only show red emission with near-unity photoluminescence quantum yield (PLQY) and high resistance to thermal quenching but also exhibit circularly polarized luminescence with an asymmetry factor (glum) of 2.5×10-3, which can be attributed to the enhanced crystal rigidity resulting from the hydrogen bonding networks between R/S-(3-hydroxy piperidine) cations and [MnCl6]4- chains. The circularly polarized luminescence activities originate from the asymmetric [MnCl6]4- luminophores induced by N-H⋅⋅⋅Cl hydrogen bonding with R/S-(3-hydroxy piperidine). Moreover, these samples demonstrate great application potential in circularly polarized light-emitting diodes and X-ray scintillators. This work shows a highly efficient photoluminescent Mn-based halide and offers a strategy for designing multifunctional chiral metal halides.

Effect of Dual-Organic Cations on the Structure and Properties of 2D Hybrid Perovskites as Scintillators.

Two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) crystals show promise as scintillating materials for wide-energy radiation detection, outperforming their three-dimensional counterparts. In this study, we synthesized single crystals of (PEA2-xBZAx)PbBr4 (x ranging from 0.1 to 2), utilizing phenethylammonium (C6H5CH2CH2NH3+) and benzylammonium (C6H5CH2NH3+) cations. These materials exhibit favorable optical and scintillation properties, rendering them suitable for high light yield (LY) and fast-response scintillators. Our investigation, employing various techniques such as X-ray diffraction (XRD), photoluminescence (PL), time-resolved (TR) PL, Raman spectroscopy, radioluminescence (RL), thermoluminescence (TL), and scintillation measurements, unveiled lattice strain induced by dual-organic cations in powder X-ray diffraction. Density functional theory analysis demonstrated a maximal 0.13 eV increase in the band gap with the addition of BZA cation addition. Notably, the largest Stokes shift of 0.06 eV was observed in (BZA)2PbBr4. The dual-organic cation crystals displayed >80% fast component scintillation decay time, which is advantageous for the scintillating process. Furthermore, we observed a dual-organic cations-induced enhancement of electron-hole transfer efficiency by up to 60%, with a contribution of >70% to the fast component of scintillation decay. The crystal with the lowest BZA concentration, (PEA1.9BZA0.1)PbBr4, demonstrated the highest LYs of 14.9 ± 1.5 ph/keV at room temperature. Despite a 55-70% decrease in LY for BZA concentrations >5%, simultaneous reductions in scintillation decay time (12-32%) may work for time-of-flight positron emission tomography and photon-counting computed tomography. Our work underscores the crucial role of dual-organic cations in advancing our understanding of 2D-HOIP crystals for materials science and radiation detection applications.

Bandgap Narrowing in Europium(II)-Based Bromide Hybrids toward Improved X-ray Scintillation and Imaging

Bandgap Narrowing in Europium(II)-Based Bromide Hybrids toward Improved X-ray Scintillation and Imaging

The Nanoplasmonic Purcell Effect in Ultrafast and High-Light-Yield Perovskite Scintillators.

The development of X-ray scintillators with ultrahigh light yields and ultrafast response times is a long sought-after goal. In this work, a fundamental mechanism that pushes the frontiers of ultrafast X-ray scintillator performance is theoretically predicted and experimentally demonstrated: the use of nanoscale-confined surface plasmon polariton modes to tailor the scintillator response time via the Purcell effect. By incorporating nanoplasmonic materials in scintillator devices, this work predicts over tenfold enhancement in decay rate and 38% reduction in time resolution even with only a simple planar design. The nanoplasmonic Purcell effect is experimentally demonstrated using perovskite scintillators, enhancing the light yield by over 120% to 88 ± 11 ph/keV, and the decay rate by over 60% to 2.0 ± 0.2 ns for the average decay time, and 0.7 ± 0.1 ns for the ultrafast decay component, in good agreement with the predictions of ourtheoretical framework. Proof-of-concept X-ray imaging experiments are performed using nanoplasmonic scintillators, demonstrating 182% enhancement in the modulation transfer function at four line pairs per millimeter spatial frequency. This work highlights the enormous potential of nanoplasmonics in optimizing ultrafast scintillator devices for applications including time-of-flight X-ray imaging and photon-counting computed tomography.

HCOO- Doping-Induced Multiexciton Emissions in Cs3Cu2I5 Crystals for Efficient X-Ray Scintillation.

Self-trapped exciton (STE) luminescence, typically associated with structural deformation of excited states, has attracted significant attention in metal halide materials recently. However, the mechanism of multiexciton STE emissions in certain metal halide crystals remains largely unexplored. This study investigates dual luminescence emissions in HCOO- doped Cs3Cu2I5 single crystals using transient and steady-state spectroscopy. The dual emissions are attributed to intrinsic STE luminescence originating from the host lattice and extrinsic STE luminescence induced by external dopants, respectively, each of which can be triggered independently at distinct energy levels. Theoretical calculations reveal that multiexciton emission originates from structural distortion of the host and dopant STEs within the 0D lattice in their respective excited states. By meticulously tuning the excitation wavelength and selectively exciting different STEs, the dynamic alteration of color change in Cs3Cu2I5:HCOO- crystals is demonstrated. Ultimately, owing to an extraordinarily high photoluminescence quantum yield (99.01%) and a diminished degree of self-absorption in Cs3Cu2I5:HCOO- crystals, they exhibit remarkable X-ray scintillation characteristics with light yield being improved by 5.4 times as compared to that of pristine Cs3Cu2I5 crystals, opening up exciting avenues for achieving low-dose X-ray detection and imaging.

Cs2NaGdCl6:Tb3+─A Highly Luminescent Rare-Earth Double Perovskite Scintillator for Low-Dose X-ray Detection and Imaging.

Rare-earth-based double perovskite (DP) X-ray scintillators have gained significant importance with low detection limits in medical imaging and radiation detection owing to their high light yield (LY) and remarkable spatial resolution. Herein, we report the synthesis of 3D double perovskite (DP) crystals, namely, Cs2NaGdCl6 and Tb3+-Cs2NaGdCl6 using hydrothermal reaction. Cs2NaGdCl6 DP single crystals exhibited a blue self-trapped exciton (STE) emission at 470 nm under ultraviolet (265 nm) excitation with a photoluminescence quantum yield (PLQY) of 8.4%. Introducing Tb3+ ions into Cs2NaGdCl6 has resulted in quenching of STE emission and enhancing green emission at 549 nm attributed to the 5D4 → 7F5 transition of Tb3+, suggesting efficient energy transfer (ET) from STE to Tb3+. This ET process is evidenced by the appearance of Tb3+ bands in the excitation spectra of the host, the shortening of the STE lifetimes in the presence of Tb3+ ions, and the enhancement of PLQY (72.6%). Furthermore, Cs2NaGdCl6:5%Tb3+ films of various thicknesses (0.1-0.6 mm) were synthesized and their X-ray scintillating performance has been examined. The Cs2NaGdCl6:5%Tb3+ film with 0.4 mm thickness has exhibited an excellent linear response to the X-ray dose rate with a low detection limit of 41.32 nGyair s-1, an LY of 39,100 photons MeV-1, and excellent radiation stability. Benefiting from the strong X-ray excited luminescence (XEL) of Cs2NaGdCl6:5%Tb3+, we developed a Cs2NaGdCl6:5%Tb3+ X-ray scintillator screen with a least thickness (0.1 mm), exhibiting remarkable imaging ability with a spatial resolution of 10.75 lp mm-1. These results suggest that Cs2NaGdCl6:Tb3+ can be a potential candidate for low-dose and X-ray imaging applications.

Organosilicon-Based Ligand Design for High-Performance Perovskite Nanocrystal Films for Color Conversion and X-ray Imaging.

Perovskite nanocrystals (PNCs) bear a huge potential for widespread applications, such as color conversion, X-ray scintillators, and active laser media. However, the poor intrinsic stability and high susceptibility to environmental stimuli including moisture and oxygen have become bottlenecks of PNC materials for commercialization. Appropriate barrier material design can efficiently improve the stability of the PNCs. Particularly, the strategy for packaging PNCs in organosilicon matrixes can integrate the advantages of inorganic-oxide-based and polymer-based encapsulation routes. However, the inert long-carbon-chain ligands (e.g., oleic acid, oleylamine) used in the current ligand systems for silicon-based encapsulation are detrimental to the cross-linking of the organosilicon matrix, resulting in performance deficiencies in the nanocrystal films, such as low transparency and large surface roughness. Herein, we propose a dual-organosilicon ligand system consisting of (3-aminopropyl)triethoxysilane (APTES) and (3-aminopropyl)triethoxysilane with pentanedioic anhydride (APTES-PA), to replace the inert long-carbon-chain ligands for improving the performance of organosilicon-coated PNC films. As a result, strongly fluorescent PNC films prepared by a facile solution-casting method demonstrate high transparency and reduced surface roughness while maintaining high stability in various harsh environments. The optimized PNC films were eventually applied in an X-ray imaging system as scintillators, showing a high spatial resolution above 20 lp/mm. By designing this promising dual organosilicon ligand system for PNC films, our work highlights the crucial influence of the molecular structure of the capping ligands on the optical performance of the PNC film.

Overcoming Thermal Quenching in X-ray Scintillators through Multi-Excited State Switching.

X-ray scintillators have gained significant attention in medical diagnostics and industrial applications. Despite their widespread utility, scintillator development faces a significant hurdle when exposed to elevated temperatures, as it usually results in reduced scintillation efficiency and diminished luminescence output. Here we report a molecular design strategy based on a hybrid perovskite (TpyBiCl5) that overcomes thermal quenching through multi-excited state switching. The structure of perovskite provides a platform to modulate the luminescence centers. The rigid framework constructed by this perovskite structure stabilized its triplet states, resulting in TpyBiCl5 exhibiting an approximately 12 times higher (45 % vs. 3.8 %) photoluminescence quantum yield of room temperature phosphorescence than that of its organic ligand (Tpy). Most importantly, the interactions between the components of this perovskite enable the mixing of different excited states, which has been revealed by experimental and theoretical investigations. The TpyBiCl5 scintillator exhibits a detection limit of 38.92 nGy s-1 at 213 K and a detection limit of 196.31 nGy s-1 at 353 K through scintillation mode switching between thermally activated delayed fluorescence and phosphorescence. This work opens up the possibility of solving the thermal quenching in X-ray scintillators by tuning different excited states.

Optical and scintillation properties of Er-doped La3Ga5SiO14 single crystals emitting near-infrared photons

0.5, 1, 2, and 5% Er-doped La3Ga5SiO14 (LGS) single crystals were synthesized by the Floating Zone method and the photoluminescence (PL) and scintillation properties were characterized. Emission peaks appeared at visible–near-infrared (NIR) regions. Their spectral features matched with those due to the 4f–4f transitions of Er3+. The PL quantum yields of 0.5, 1, 2, and 5% Er-doped samples were respectively 45.0, 73.3, 82.5, and 69.4%. The decay times due to the 2H9/2–4I15/2 transitions of Er3+ were obtained when visible ranges were monitored under excitation of both visible lights and X-rays. All the prepared samples showed good linearity between the X-ray exposure dose rate and scintillation signals in NIR ranges. The best lower detection limit in prepared samples was 5 mGy/h recorded by the 2% Er-doped LGS.

Through-Space Charge-Transfer Organogold(III) Complexes Enable High-Performance X-ray Scintillation and Imaging.

Organic scintillators have recently attracted growing attention for X-ray detection in industrial and medical applications. However, these materials still face critical obstacles of low attenuation efficiency and/or inefficient triplet exciton utilization. Here we developed a new category of organogold(III) complexes, Tp-Au-1 and Tp-Au-2, through adopting a through-space interaction motif to realize high X-ray attenuation efficiency and efficient harvesting of triplet excitons for emission. Thanks to the efficient through-space charge transfer process, this panel of complexes achieved higher photoluminescence quantum yield and shorter radiative lifetimes compared with the through-bond reference complexes. Inspiringly, these organogold(III) complexes exhibited polarity-dependent emission origins: thermally activated delayed fluorescence and/or phosphorescence. Under X-ray irradiation, Tp-Au-2 manifested intense radioluminescence together with a record-high scintillation light yield of 77,600 photons MeV-1 for organic scintillators. The resulting scintillator screens demonstrated high-quality X-ray imaging with >16.0 line pairs mm-1 spatial resolution, outstripping most organic and inorganic scintillators. This finding provides a feasible strategy for the design of superior organic X-ray scintillators.

Multiphase Transformation in Hybrid Copper(I)-Based Halides Enable Improved X-ray Scintillation and Real-Time Imaging

Multiphase Transformation in Hybrid Copper(I)-Based Halides Enable Improved X-ray Scintillation and Real-Time Imaging